The Bati had the lead 16-8 at the break but the Kumuls stormed home to win 24-22.
Papua New Guinea‘s halfback Watson Boas scored a double and his brother Ase kicked four goals.
But it was the Kumuls defence that shone, the team pulling off some brilliant tackles to deny the Fijian attack.
Papua New Guniea were first to score, Boas collecting his own bomb to touchdown. They were soon in again through fullback David Mead.
The Bati hit back through Etuate Qionimacawa who grabbed two tries to finish off the half.
In the second 40 the Kumuls stepped up a gear, Kato Ottio crashing over and then Boas got his double.
Nene MacDonald was the next to touch down, before Qionimacawa’s third try of the night made it a tense finish in what was a special evening for PNG.